I was wondering if anyone else is having the battery percentage getting stuck? Mine will get stuck then after it's been locked for a few minutes, the % will be down by over 5% or more. I'm on iOS 9.3.2.
Nope, never had that problem before. Try restarting the device?
I have and even restored as a new device. This is a frustrating problem.
If you're having battery issues I recommend contacting Apple Support or taking your 6s into an Apple Store. You're still under warranty.